Q: I don't love how the flows were laid out. Can anything be done about that?

A: The layout algorithm of the D3 Sankey library can depend on the order of the Nodes and Flows in some mysterious ways. If you don't like the layout it produced, experiment with changing the order you listed your Flows in.

Beyond that, you can drag Nodes around to reposition them before you export. (However, changing any inputs will re-draw/reset the whole diagram, so save the dragging for the last step before you export.)

Q: I can't enter negative flow amounts (or 0 for that matter), and it doesn't work to have a Node flow into itself or into a Node to its left.

A: True. The D3 Sankey library does not support those types of inputs at this time, and therefore this tool does not either.

Q: Why does the diagram take so long to be drawn when I make a change?

A: Check the Export control panel section and change the scale to ‘1x’ while you iterate on your design. After every change, the PNG is re-created in the background, so working with 4x (or even 2x) can be a bit slow at times. If the speed is unsatisfactory, save the scaling-up step until you are finally ready to export.

Q: Does SankeyMATIC send a copy of my data anywhere?

A: No. All processing of the data is done locally in your browser with JavaScript (including the generation of the PNG file), so I am not told what you are doing with the tool unless you tell me yourself.